Global particulate matter pool temporal variability over the SeaWiFS period (1997-2007)
Résumé
Major patterns of temporal variability associated with marine particulate backscattering coefficient at 490 nm (b bp(490), an indicator of the particulate organic carbon concentration) and particle backscattering spectral dependency γ (a proxy for the relative proportion between small and large particles) are investigated with a 10-year SeaWiFS series. Generally, the contribution of the seasonal cycle to the series variance has a similar spatial pattern for γ and the chlorophyll a concentration (Chl a). The spatial distribution of significant monotonic changes for γ and Chl a (reaching up to ±5% yr −1) is also comparable with opposite signs of the slope, indicating that inter-annual changes in Chl a and average particle size are often positively correlated. Conversely, spatial patterns of seasonality and trend found for b bp(490) often differ from those of Chl a and γ. Particularly, large seasonal signals for b bp(490) are seen poleward of 45° while high seasonality for Chl a and γ is found in two mid-latitude zonal belts (∼20°-40° latitude). Significant changes in b bp(490) over the considered decade are much fewer and usually not significant in areas where strong positive or negative changes in Chl a have been detected. This suggests that the changes in phytoplankton have not been translated in terms of overall particle stock
Domaines
Océanographie
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